Say you type “cancer” into your search engine and click on the result Cancer.com. At the bottom of the page, you see the logo of the nonprofit American Cancer Society (ACS). So is Cancer.com the ACS’s website?

Not at all. The American Cancer ­Society site is Cancer.org, not Cancer.com. Nor have you landed on the website of the National Cancer Institute. That one is Cancer.gov. In truth, Cancer.com is a commercial site put up by the drug manufacturer Janssen, owned by Johnson & Johnson. That doesn’t necessarily mean it’s biased or misleading. Cancer.com includes reliable information from reputable organizations. But it’s worth knowing who funds a site because it may affect what information is presented. More confusing website domain names…

Health.com vs. Health.gov. The former is run by the publisher Time, Inc., and includes articles about celebrities, for example. The latter is the US government’s website to educate the public about health issues.

Vaccines.com vs. Vaccines.gov. The .com is run by Sanofi Pasteur, a vaccine manufacturer. The latter belongs to the US Department of Health and Human Services.

Healthcare.com vs. Healthcare.gov. The .gov site is the only federal site that lets you apply for subsidies under the Affordable Care Act. The .com site is a commercial site that earns money from advertisers and companies hoping to sell you health insurance.

To avoid confusion, especially on a topic as important as health, give yourself a refresher on web name suffixes. A “.com” usually is a commercial site, although it may provide accurate information. (Editorial note: Our own site, BottomLineInc.com, has strict guidelines that protect editorial content from commercial influence.)

Other web suffixes include…

.gov. A government site, often a good place to start a health search.

.edu. Academic institutions use this one—another good source.

.org. These sites are run by organizations, usually (but not always) nonprofit. Their trustworthiness varies and may be influenced by where they get funding.